Method of making hexagon socket type cup point set screw blanks



Nov. 19, '1957 R. e. FRIEDMAN 2,813,279

METHOD OF MAKING HEXAGON SOCKET TYPE cumomw SET SCREW BLANKS Filed. Aug.14.. 1953 INV EN TOR. EOBEIE'T G 'FE/E'DMA N iP/CHE Y, WA 7' 75 EDGE)?701v? M NENAI v A 77'ORNEYS s Patent ()fi 2,813,279 Patented Nov. 19,1957 METHOD OF MAKING HEXAGON SOCKET TYPE CUP POINT SET SCREW BLANKSRobert G. Friedman, Tiflin, Ohio, assignor to The National MachineryCompany, Tiflin, Ohio, a corporation of Ohio Application August 14,1953, Serial No. 374,328

5 Claims. (Cl. -10) This invention relates generally to forming metalarticles and more particularly to the forging of set screw blanks byprogressive forging operations.

It is an important object of this invention to provide amethod forforging set screw blanks which permits the utilization of high speed lowcost forging methods in the production of such blanks.

It is another object of this invention to provide a method of forgingset screw blanks which results in a set screw blank having closetolerances and greater strength and hardness than set screws formed byordinary machining methods.

'It is still another object of this invention to provide a method forforging set screw blanks wherein the corners and edges of the blank areproperly filed out and formed.

The foregoing and other objects and advantages will become apparent inview of the following description taken in conjunction with thedrawings, wherein:

Fig. 1 is a plan view of the various stations of a forging apparatusincorporating this invention; and

Figs. 2, 2a, 2b, 2c, and 2d are enlarged cross sectional views showingthe blank at each of the stations shown in Fig. 1.

A method of forging set screws according to this invention comprisesforging one end of a blank with high pressures to produce a sharplyfilled contour without excessively work hardening the remainder of theblank and then piercing a hole into the other end of the blank.Preferably the desired point is formed on one end of the blank by doubleblow heading and a polygonal hole is then pierced into the previouslyworked portion of the blank which is to be externally threaded and theentire operation is carried out in a progressive header or the likewithout the necessity of intermediate annealing. The embodiment[disclosed includes the steps of cutting a blank from wire or rod stockand positioning it in a first forging station wherein a portion of theblank adjacent to one end is upset forming an axial conical recess andan outer conical surface. The blank is then inserted in the secondforging die station wherein the one end described above is furtherforged so as to form a relatively flat external conical surface and theother end.

may be recessedto provide an internal conical surface. That portion ofthe blank adjacent to the space between the two dies at the secondstation is extruded into the opening thereby forming a flash to relievethe excessive pressure formed at this die station. The blank is thentransferred to still another die station wherein the blank is pressedover the end of a polygonal punch thereby forming a polygonal socket insaid other end of the blank.

The blank is then transferred to the final station wherein the flash istrimmed thereby providing a finished set screw blank ready for externalthreading about the socketed portions.

The process according to this invention is adapted to be carried out bya multistation header wherein appropriate transfer members are suppliedto transfer the blank progressively from one station to the next. By

utilizing such a machine a large number of blanks may be rapidly forgedthereby substantially reducing the unit cost of the completed blank.

In order to insure complete filling of the corners of the dies thisinvention contemplates the formation of flash in the second forgingstation. By providing more metal in the initial blank than is necessaryto fill the dies for the completed blank an extremely high pressure onthe blank as it is forged is insured. The excess metal is permitted toflash out between the dies thereby resulting in very accurate control ofthe finished blank with the results that relatively close tolerances maybe maintained. In the past for forging of items such as set screw blanksdifliculty has been present in insuring that the points or edges of theblank are properly filled and the use of excessive metal in the initialblank as described above has resulted in the elimination of thisproblem.

For a more complete understanding of this invention reference should bemade to the drawings wherein the cut-off station designated as 10 isprovided. The stock is preferably supplied in the form of wire or rodstock 11 which is fed through the bore 12 in the cut-off station 10. Thestock feeds through the bore 12 and projects beyond the forward face ofthe die breast 9 as shown in Fig. 1. Suitable feed and stop means areprovided but for purposes of simplicity are not shown in the drawings.The shearing member 13 engages the stock projecting beyond the diebreast 9 and shears otf a blank 14 from the stock 11. The blank 14 isthen positioned in front of the first forging die 16 which is formedwith a first bore 17 having substantially the same diameter as thediameter of the stock. The inner end of the first bore 17 terminates inan inclined or transition section 18 which is adapted to form a chamferon one end of the blank. The knockout pin 19 is positioned with itsforward face adjacent to the inner end of the transition section 18 andforms the bottom of the cavity in the die 16. The arrangement of the die16 and the knockout pin 19 provides for the admission of a portion ofthe blank into the die cavity leaving an outer portion projecting beyondthe die face 6. This outer portion is upset by the movable die 21mounted on the header slide schematicallyshown at 22. The movable die 21is 1 relatively flat conical recess 29 in the end thereof formed by thepunch 26 and an outer conical surface 31. The transition section 18 alsoforms a chamfer 32 on the other end of the first intermediate blank 28thereby eliminating any sharp edges. In the preferred embodiment thepuch is biased toward the die breast 9 by the spring 33 so that itprojects beyond the movable die 21 when the header slide is spaced fromthe die breast. This structure is utilized so that the punch 26 willengage the blank before the header slide reaches the forward positionthereby securing control of the blank and permit-. ting the withdrawalof the transfer fingers. The transfer mechanism is not shown for thepurposes of simplification. As the header slide recedes the firstintermediate blank 28 is ejected from the die 16 by the knockout pin 19into transfer fingers which transfer the first intermediate blank to thesecond forging station where the blank is positioned in front of thesecond forging sta tion 34.

having a diameter substantially equal to the bore 17. A

knockout-pin 37 is positioned in the bore 36 and is formed wit-h a-conieal punching end surface '38 "which is positioned at a point spacedfrom the face of the die 34. The movable die 39 is mounted on the headerslide 22 and -is formed with 121 relatively flat conical die cavityPP-Which is c'oaxial w-ith the bore 36. The inner end of the conical diecavity 41 terminates in' a 'bore ll in whieh the punch 43 i'spositioned, The'punch43, like thepuntqh 26, is formed with a eonical'punch-ing "end-surface 44: which projects in'to the "cavity 41. Theforward end surface 38 of'thekno'ekout pin"37' cooperatio'nwith thedie'34 forms a 'd-ie'cavity 'adapted to receivethe portion oi the firstintermediate blank =28 which is not upset'and the upset port-ion withthe surface ofthe' recess *29"arid the surface 31 project beyond theforward i face of the die '34z "When the header-sli'de reaches theforward positionedjacentl' to the die breast 9 the' projecting'p'ortionof the first intermediate blank -28 is engaged? by the punch 43 and" thediei39 thereby upsetting the projecting portion to form the conicalrecess 46 and-a relativelyflat-outer'conical-surface 47 which intersectsat an annular edge 1.-8. The action-of the die 39 and'the'punch 43ampresses the blank against the end surface 38'of the knockout pin "37'thereby forming an axial recess 49 in the rearward-end of the blank.Since the 1 knockout 1 pin" 37 is radially supported by'the bore 36inthe die 34 therecess-49 is accurately located. -In'ord'ertoiris-ure-that' theannul-aredge 48' is properly filledthediesatthesecondforging station are proportioned so that the-excess r'netali'n:the first intermediate blank 28 will flash out between the forwardsurface ofthe dies 94 and 39-. By supplyingan excess of metallargecompression forces on the blank arei'nsured which result in aproperly filled out' annular edge4 8 and byproviding for the flash 51uniformity of thefinal blank wherein the tolerances are closelymaintained isinsuredz,

The second intermediate blank 52 is thus fo'r'm'edby the dies in thesecond forging station which has theforward end shape substantiallyformed as it will appear in the finished set screw blank. The spring 53in the second forging die station operates much the sameway as thespring 33 in the first forging die station and operates to bias thepunch 43 toward the forward position when the header slide isnotadjacent to the die breast'9 and the knockout pin 37 is used to ejectthe second intermediate blank from the die 34 as the header slide movesaway from the die breast 9 after the completion of the forging at thisstation.

Transfer fingers move the second intermediate blank to thethirdforgingdie station where the'blank is pierced to form the polygonal cavity ofthe finished set screw blank. The sliding die 541s mounted i'nthediebr'east 9 and-is'adapted for limited reciprocation therein. A heavyspring 56 biases the die 54 toward the forward position adjacent to theface of the die breast 9 and a ball type stop-means -57 may be utilizedto limit the amount'of r'eciprocation of the die 54. The 'die54 isformed with a bore 58 having substantially the same diameter as thebores 36 and 17. A piercing tool 59 is mounted within the bore 58 and isarranged sothat it is held stationary relative to the die breast 9during the forging operation in the third forging die station. Themovable die 61 is mounted on the header slide 22 and is formed'with adie cavity 62 having substantially the same shape as the die cavity 41.Again, a puch 63 is mounted in the movable die '61 with aprojectingconical end surface extending into the die cavity 62. As theheader slide moves toward the-forward position adjacent to the diebreast 9 the movable die 61 andthe punch'63 engage the end of thesecondintermediate blank 53 forcing the blank into the bore58 of thedie'54until the'flash 51' engages theforward -face of both'of the dies.The sliding die'54 and the blank recede asthe header slide continues toadvance. In the preferred embodiment the forward end of the punch orpiercing 001 59 then engages the rearward'e'nd'of the secondintermediate blank 52. Since the recess 49 in the rearward'end of thesecond intermediateblank"52'is"acthe rearward end of the blank therebyforming the third intermediate blank 66. Here again, a spring 67 isutilized. to bias the punch 63 toward thedie breast 9. After the headerslide 22 has moved away from the die breast 9 t the completion of theforging stroke the piercing tool 59 moves outwardly relative to the diebreast 9-carryii1g the third intermediate blank 66 out of thesliding die54. At this time a stripper means which is not shown for purposes ofsimplification grips the third intermediate blank 66 and strips it fromthe piercing tool 59 as the piercing tool returns to its initialposition.

Transfer fingers then transfer the third intermediate blank 66 to thefourth die station. A shearing die 68 is mounted at the'fourth diestation and is formed with a bore'69 having a diameter substantiallyequal to the diameter of the bore 58 in the'die 54. A punch 71 mountedin the header slide coaxial with the bore 59- and isformed with adiameter slightly less than the diameter of the bore 59 and a forwardface adapted to fit into the conical recess 46. As the header slidemoves towardthe die breast'9 the punch 71 engages the third intermediatethe flash 74 from the punch 71. Thereafter the knockout punch 76 ejectsthe finished blank from'the die 68 whereupon the blank is transferred toany further operation such as threading and the like which'must beperformed to complete the finished set screw.

By providing the rearward recess 49 to guide t he piercing tool 59during the initiation of the piercing blank an "accurately locatedpolygonal hole is foreseen the finished blank. Also, by utilizing thesliding die 54 a longer die life is insured since the sliding actionbetween the. blank and the die is r'educed'toaniininium.

By forming met screw blank according to this invention the nietal'iswork-hardened thereby permittingthe use of low cost materials for themanufacture ofthe blank whereas in "earlier 'metho'ds wherein the blanksare cut by screwmachines or'the like no appreciable-workhard ening waspresent to improve the quality of the finished screw blank. The portionof the'blank forming thepoint is subjected to high'pressures and to adouble blowheading operation filling out the COhtbuIQShEI'plYflIldcleanly and providing substantial work hardening. The remainder of the"blank'which is to be socketed is: protected from high forging pressuresduring the forming of the point so that it is not substantially workhardened prior to *the socketing operation thereby avoiding thenecessity of'any' intermediate annealing and avoiding hardening thesockete'd portion to suchan extent as to interfere with subsequentthreading. I I

Having completed a detailed description'of a preferred embodiment ofthepresent invention so that others skilled in the art maybe able tounderstand and practice the same, I state that what I desire to secureby Letters Patent-is not limited by said preferred embodiment but ratheris definedin what is claimed.

What is claimed is:

1. That method of making a socketed set screw having a cup point-whichcomprises upsetting one end of acylindrical blank to form acylindrical-shank portion. and a conical head portionhaving its maximumdiameter at the juncture between the head and the shank and having areversely disposed conical recess at the end face of the head portionand thereafter pressing the blank axially between a cylindrical dieconfining the shank and a die conforming to the head portion, forming anannular flash at the juncture between the head and the shank andthereafter piercing a hex socket in the shank portion while the blank isgripped across said annular flash and axially supported at said head endand thereafter trimming the flash from the blank.

2. That method of making a socketed cup point set screw which comprisespreliminarily upsetting a cylindrical blank to provide a head portionand a shank portion, said shank portion being confined during saidupsetting in a cylindrical die wherein the bottom portion of thecylindrical die is provided with a chamfer to form a chamfer in the endof the shank portion and wherein said upsetting of the head is effectedby a conical die sloping from a maximum diameter to a minimum diameterat the end face of the head portion of the blank and wherein the endface of the head die is provided with a conical point and thereafterpressing said blank axially between dies confining the head and shank tofurther upset said head and forming an annular flash at the juncturebetween the head and shank at said maximum diameter section andthereafter piercing the chamfered end of the shank of the blank axiallyby forcing a hex punch into the end face of the blank a distancecorresponding to the distance from the end face of the shank of theblank to said annular flash and thereafter trimming the blank by forcingthe same through a trim die having a maximum diameter corresponding tothe diameter of the pierced shank portion of the blank.

3. That method of forming a cup pointed socketed set screw blank whichcomprises preliminarily upsetting a conical head on a cylindrical blankwhile a part of the cylindrical blank is confined by a cylindrical dieand wherein the tool upsetting the head is provided with a conicalrecess having a maximum diameter greater than the maximum diameter ofthe shank portion of the blank and the central portion of the headupsetting tool is provided with a point to form the cup point of thefinished article and thereafter axially pressing the blank with the headand shank confined to further upset said head and forming an annularflash at the juncture between the upset head and the shank andthereafter piercing the shank portion of the blank with a hex tool whilethe flash portion of the blank is gripped between co-operating diesconfining the head of the blank and the cylindrical side walls of theshank and thereafter trimming the flash from the blank by gripping theflash between co-operating dies and moving the blank axially into one ofsaid co-operating dies by a punch on the other whereby the flange isimpaled on the punch.

4. That method of making a socketed cup point cap screw which comprisesholding the major portion of a cylindrical blank in a cylindrical dieand leaving a portion of the blank projecting from said cylindrical dieand preliminarily upsetting said projecting portion to a diametergreater than said shank portion, the tool upsetting said head portionhaving a central conical point to indent the head portion of the blankto a depth corresponding to the depth of the cup point in the finishedarticle and thereafter confining the upset blank between the pair ofco-operating dies, one die being shaped to conform to the shank portionof the blank and the other die being shaped to conform substantially tothe cup point of the finished article and moving said dies toward eachother to further upset said head and forming an annular flash at thejuncture between the shank and the tapered point of the finished articleand thereafter forcing the blank through a trim die having a circularopening wherein the diameter of the opening corresponds to the diameterof the shank portion of the blank whereby the flash is trimmed from theblank.

5. That method of forming a socketed cup point set screw having a hexsocket through the major portion of its length and a point sloping fromthe maximum diameter of the set screw blank toward one end face whichhas a cup point therein which comprises confining the major portion of acylindrical blank in a cylindrical die and upsetting the projecting endportion of the blank which ultimately forms the cup point of the setscrew, said upsetting operation being effected by a conical tool havinga central pointed area to form the cup point and thereafter compressingthe blank axially to flow a portion of the upset metal outwardly into anannular flash and at the same time reducing the upset portion betweenthe flash and the cup point of the blank substantially to the dimensionsof the finished article and thereafter confining the metal of the blankhaving the flash thereon by gripping the blank across the flash andconfining the head and side walls of the blank while a hex tool isforced into the end face of the blank opposite the cup point, said hextool having a point which moves axially into the blank a distancecorresponding to the distance between the flash and the pierced end ofthe blank and thereafter trimming the flash from the blank by forcingthe blank through a trim die having a diameter correspondingsubstantially to the diameter of the pierced portion of the blank.

References Cited in the file of this patent UNITED STATES PATENTS1,388,566 Hinchcliff Aug. 23, 1921 1,832,164 Wilcox Nov. 17, 19311,978,371 Purtell Oct. 23, 1934 1,978,372 Purtell Oct. 23, 1934-2,239,352 Cherry Apr. 22, 1941 2,294,802 Reich Sept. 1, 1942 2,396,995Friedman Mar. 19, 1946

